Unit Test cases for authentication statistics implemented as part of jira item SEBA-37

Add unit testcases for testing below statistics, implemeted in seba-37.

 
 
–Roundtrip packet time to the accounting server

–Number of access request packets sent to the server

–Number of access request packets retransmitted to the server

–Number of access accept packets sent to the server

–Number of access reject packets sent to the server

–Number of access challenge packets sent to the server

–Number of malformed access response packets received from the server

–Number of access response packets received from the server with an invalid validator

–Number of access request packets pending a response from the server

–Number of packets of an unknown RADIUS type received from the accounting server

–Number of dropped packets received from the accounting server

–Number of packets received from an unknown server